Deformation history of the white range duplex, central australia, with implications for fold reorientation

The White Range area in the Arltunga Nappe Complex, central Australia, is one of the northernmost exposures of Heavitree Quartzite caught underneath a large south-directed crustal nappe (the Paradise Nappe) emplaced during the Late Palaeozoic Alice Springs Orogeny. Structural, microfabric and strain analyses of the White Range area show that sub-horizontal foliation north-south lineation, and north-south isoclinal recumbent folds were produced during movement of the overlying Paradise Nappe. The strain history involved components of thrust, wrench and pure shear and the relative proportion of each component was analysed using the relationship between finite strain and fold hinge orientation. A reasonable solution is one in which thrusting dominated over wrenching, with a pure shear in the vertical plane responsible for syn-thrusting extension in the shear direction. This result may indicate the relative weakness of mid-crustal rocks that collapse under the weight of the thrust system and flow in a direction transverse to the thrust belt.